نتایج جستجو برای: atomic density

تعداد نتایج: 492062  

In this study, the geometries of the [SiNinHn]q and [SiCunHn]q clusters, (n = 4,5,6 and q = 0,+1,-1) complexes have been optimized to form complexes with four, five and six planar and nonplanarsubstituents, with negative, neutral or positive atomic charge, using Density FunctionalTheory (DFT) at B3LYP/6-311+G (3df, p) computational level and then their thermodynamicstability were investigated b...

Journal: :geopersia 0
kazem saadat ripi,production research center hossain rahimpour-bonab university of tehran mohammad reza esfahani ripi,production research center jafar vali ripi,production research center

for obtaining reservoir petrophysical properties, for example porosity, non-destructive methods such as x-ray computed tomography, ct, seems to be precise and accurate. porosity is deducted from the ct image with a single scan via different techniques, such as pore space detection by image segmentation techniques then correlation with porosity. more than one hundred samples with carbonate litho...

Journal: :Physical review letters 2004
C von Cube S Slama D Kruse C Zimmermann Ph W Courteille G R M Robb N Piovella R Bonifacio

Networks of globally coupled oscillators exhibit phase transitions from incoherent to coherent states. Atoms interacting with the counterpropagating modes of a unidirectionally pumped high-finesse ring cavity form such a globally coupled network. The coupling mechanism is provided by collective atomic recoil lasing, i.e., cooperative Bragg scattering of laser light at an atomic density grating,...

2008
D. J. Goorskey Hai Wang W. H. Burkett Min Xiao D. J. GOORSKEY HAI WANG W. H. BURKETT MIN XIAO

Atomic media inside an optical cavity can significantly alter the spectral response of the cavity. Both theoretical and experimental examinations are made of the cavity transmission with a highly dispersive intracavity multilevel atomic medium. It is found, owing to the reduced absorption and steep dispersion change accompanying electromagnetically induced transparency in such a multi-level ato...

Journal: :Journal of Computational Chemistry 2001
Marcel Swart Piet Th. van Duijnen Jaap G. Snijders

A new charge analysis is presented that gives an accurate description of the electrostatic potential from the charge distribution in molecules. This is achieved in three steps: first, the total density is written as a sum of atomic densities; next, from these atomic densities a set of atomic multipoles is defined; finally, these atomic multipoles are reconstructed exactly by distributing charge...

Journal: :Journal of computational chemistry 2004
Célia Fonseca Guerra Jan-Willem Handgraaf Evert Jan Baerends F. Matthias Bickelhaupt

We present the Voronoi Deformation Density (VDD) method for computing atomic charges. The VDD method does not explicitly use the basis functions but calculates the amount of electronic density that flows to or from a certain atom due to bond formation by spatial integration of the deformation density over the atomic Voronoi cell. We compare our method to the well-known Mulliken, Hirshfeld, Bade...

2011
Chen-Lung Hung Xibo Zhang Li-Chung Ha Shih-Kuang Tung Nathan Gemelke Cheng Chin

We present a complete recipe to extract the density–density correlations and the static structure factor of a two-dimensional (2D) atomic quantum gas from in situ imaging. Using images of non-interacting thermal gases, we characterize and remove the systematic contributions of imaging aberrations to the measured density–density correlations of atomic samples. We determine the static structure f...

Journal: :The Journal of chemical physics 2004
C A Ullrich Kieron Burke

Time-dependent density-functional theory in the adiabatic approximation has been very successful for calculating excitation energies in molecular systems. This paper studies nonadiabatic effects for excitation energies, using the current-density functional of Vignale and Kohn [Phys. Rev. Lett. 77, 2037 (1996)]. We derive a general analytic expression for nonadiabatic corrections to excitation e...

1998
K. Yabana

The time-dependent local-density approximation (TDLDA) is shown to remain accurate in describing the atomic response of group IB elements under the additional approximation of using pseudopotentials to treat the effects of core electrons. This extends the work of Zangwill and Soven who showed the utility of the all-electron TDLDA in the atomic response problem.

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